Doug Mulvihill, marketing manager, UK and Ireland, of Ringover, discusses the future of telephony and how construction companies can prepare for the PSTN switch off

At the end of 2025, the public switched telephone network (PSTN) will be switched off, leaving many businesses that rely on the PSTN without a means to communicate. With love for the traditional landline dwindling, how can construction, an industry that relies heavily on seamless communication, prepare for this overhaul?

From the technology in mobile phones to the hidden infrastructure used to power landlines, telephony is constantly changing. The dial-up modem, which connected servers via public telephone networks, was an internet revelation introduced in the UK in 1992. But developments in internet connection deemed the modem obsolete. And in three years, we’ll be witnessing the extinction of another era of communication history — the PSTN.

The PSTN was first introduced in 1875 as the sole enabler of telephony. Even today, it still forms a large part of the UK’s telephony infrastructure, connecting voice calls using analogue signals. Over time it was partially digitalised with the introduction of the integrated services digital network (ISDN), which allowed digital signals to use the PSTN to transmit voice data. If your business’ phone calls are handled by a private automatic branch exchange (PABX) system, it’s probably connected to a telephone network using an integrated services digital network (ISDN).

Since the introduction of the ISDN, digital signals have typically been used to transmit voice calls, giving the impression that the nation’s telephony system is fully modernised. But ISDN still relies on the PSTN to operate — the same infrastructure that was installed in the 1800s. Now, the PSTN is deemed a legacy system. The equipment used to run it is aging, difficult to maintain, and many of the components used in the infrastructure are becoming obsolete.

As digitalisation takes hold of all industries, telephony is no different, and BT has decided to switch off the PSTN and encourage all customers to go digital.

When will the PSTN be switched off?

The PSTN will be completely switched off by December 2025. Although this is over three years away, BT has already started to wind down products and services across the UK. Salisbury and Mildenhall are both pilot locations for the switch off, and a stop sell of all PSTN-based products began in Salisbury in December 2020 and Mildenhall in May 2021. The PSTN will be completely withdrawn from both locations by December 2022.

When products that use the PSTN are no longer available it’s known as a stop sell. Openreach is gradually expanding the reach of the stop sell across the UK is planning to complete the national stop sell by September 2023. After this date, no new PSTN/ ISDN phone lines will be available to purchase. It won’t even be possible to change the address or business premise of an existing line.

The maturity of the PSTN and the development of new telephony technology means that it’s no longer necessary to have separate networks for the internet and phone lines. The PSTN is surplus to requirements. Instead, all services traditionally carried on the PSTN — voice data video and broadcasting — must switch to Internet Protocol (IP). So, for construction companies currently using PSTN/ ISDN phone lines, it’s crucial to establish a withdrawal strategy now.

What modern telecoms solutions will replace the PSTN?

To help prepare for the switch off, it’s important to know the modern telecoms solutions that can replace the PSTN. In this instance, businesses need to find an internet-based alternative for their communication requirements. Here, the answer lies in Voice over Internet Protocol (VoIP).

When you start a VoIP call, your phone communicates with the VoIP service provider and connects you to the desired party by exchanging data packets over the internet. Then, the VoIP phone converts the digital signals back into audio that you can hear. What’s more, with VoIP any device works as a phone. Desktops, laptops and tablets all work as VoIP devices as long as they have an internet connection.

The need for a new system is gaining traction across the country. Ringover predicts that the landline will become extinct by November 2028. Back in 2013, there were more than eight million landlines in UK workplaces, but this figure now sits at just 4.98 million. Numbers are predicted to fall below two million in spring 2024 and drop under one million in early 2026. VoIP is the technology that will replace the traditional landline.

Switching from PTSN to VoIP

Although construction is one of the largest industries in the UK, it’s surprisingly one of the least digitalised. Research by IDC and Autodesk found that while almost 75% of construction firms say digitalisation is a priority to improve their processes, only 13% are well on their way to achieving this. However, VoIP has the potential to change this. As well as futureproofing your business and migrating away from the old PSTN, switching to VoIP offers several additional features and benefits for the construction industry.

In construction, where remote working has been practised for many years, VoIP is a wise choice. Mobile devices are crucial to keep dispersed teams connected during projects, but managing multiple people can be challenging when there is an unreliable connection in rural areas. As VoIP works independently from local power availability, workers can enjoy high-quality voice calls with almost 100% connection uptime, as long as there is a stable internet connection. This enables project managers to maintain a direct link to employees located on, and off-site — instantly improving the line of communication between the workforce and supporting business objectives.

It also gives employees the flexibility to work from anywhere, as long as they have a device with VoIP phone service software downloaded. Companies can even adopt a bring your own device (BYOD) policy, meaning employees can use their own preferred device and still be contactable while travelling or working from a different location. This also reduces onboarding time because workers are already familiar with their devices and save costs on purchasing devices for workers.

A VoIP system can be integrated with other business software applications, supporting construction project management even further. For example, productivity integrations such as those that support time management can help contractors handle projects more efficiently through a drag-and-drop scheduler and real-time reporting to streamline workflows. This provides greater visibility into project worker performance and project completion from a mobile device at any time or location.

VoIP is also ideal in the case of unpredicted power outages. By ensuring access to a backup power source, workers can still access the information they need from any internet connection or mobile device, ensuring minimal downtime. Furthermore, adding new lines and scaling the system as your business grows takes just a few minutes, and is less costly as there are no maintenance costs associated with VoIP because the hardware is located offsite in a data centre.

You might feel like the PSTN switch off is tomorrow’s problem, but making the switch now will prevent any unexpected disruption when migrating to the internet-based phone system. In an industry that relies on seamless communication between workers on, and offsite, VoIP has the ability to enhance multiple areas of a construction business.

The future of telephony is VoIP, and construction will have to make the switch at some point — it’s just a matter of when. But those that are switched on will do so sooner rather than later to avoid services being switched off.


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